Purification and analysis of poly(amino acids), such as proteins, for example, may be employed in various biological studies. Generally, in protein purification and analysis, a mixture of proteins may be separated into distinct protein molecules and the separated protein molecules may be quantified. Using such processes, researchers may detect and/or identify various proteins and may study how proteins are expressed and/or modified in a biological system. The expression level and/or modification of various proteins may be correlated with biological phenotypes and/or disease states. Protein purification and analysis may thus have useful application in the diagnosis and/or prognosis of disease.
Sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) is a method that may be used in the separation and quantification of proteins. In such a method, a protein sample may be placed in denaturing and reducing conditions and heated such that the proteins unfold. The unfolded proteins may be coated with sodium dodecyl sulfate (SDS) detergent molecules, such that they take on an overall negative or anionic charge that is proportional to the size of the proteins. The SDS-coated proteins may be loaded onto a gel matrix and placed in an electric field, such that the negatively or anionically charged proteins migrate towards a positively or cationically charged anode electrode and separate into bands according to their molecular sizes. Since most proteins are colorless, the separated proteins may be stained using a protein stain that imparts color to the proteins, such as an absorption color that is light-absorptive in the presence of light, a fluorescence color that is fluorescent in the presence of light, or a luminescence color that is luminescent in the presence of light, for example. Stained proteins may be visualized, sensed, or detected in the presence of light.
Various protein stains may be used to stain proteins. For example, there are various protein stains that may be used to stain proteins that may be associated with, such as being present on or in, for example, gels or other media. Examples of protein gel stains include a stain comprising a silver compound, which may be referred to as a silver stain, Coomassie Blue (CB), which is an absorption color-based stain, and SYPRO Orange, SYPRO Red, and Deep Purple stains, which are fluorescence color-based stains. Each of these stains is associated with various disadvantages, such as those mentioned in U.S. Pat. No. 6,316,267, for example.
The foregoing may also apply to poly(amino acids), of which proteins and peptides, for example, are subsets. Development of applications, such as staining, detection, and/or identification, for example, of substances, such as poly(amino acids), peptides, and/or proteins, for example, useful compositions therefor, the making thereof, the use thereof, and/or associated technology is generally desirable.